The Man (Edmond O'Brien) is the accomplice of Marian Forbes (Laraine Day), the spurned mistress of a tycoon. She coaches The Man in impersonating the voice and appearance and habits of the intended victim and when he has been taken care of The Man begins his masquerade in a Mexican resort. Here he meets Corey Scott (Julie London) and moves on to contemplating the murder of his tutor. But things begin to go awry.